It takes 11.4 days⇒three half-lives
Further explanationGeneral formulas used in decay:
[tex]\large{\boxed{\bold{N_t=N_0(\dfrac{1}{2})^{t/t\frac{1}{2} }}}[/tex]
T = duration of decay
t 1/2 = half-life
N₀ = the number of initial radioactive atoms
Nt = the number of radioactive atoms left after decaying during T time
t1/2=3.8 days
No=4.38 μg
Nt=0.55 μg
[tex]\tt 0.55=4.38\dfrac{1}{2}^{t/3.8}\\\\0.125=\dfrac{1}{2}^{t/3.8}\\\\\dfrac{1}{2}^3=\dfrac{1}{2}^{t/3.8}\\\\3=t/3.8\rightarrow t=3.8\times 3=11.4~days[/tex]
A control is....
A: What we measure
B: What we change
C: What we measure that does not have the variable we are testing.
D: What we conclude
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Answer:
here's your answer...
Explanation:
Full moon, also hey lol.
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Answer:
B) 6 Newtons
Explanation:
Applied Force = 10 N
Resistive Frictional Force = 4 N
As we know that frictional forces always act in the opposite of the relative motion [force], and that opposite forces always subtract.
Hence,
The Net Force acting on the block = 10 N -4 N = 6 Newtons
Answer: The Answer is B
why carbon is a basic thing to classify as organic and inorganic compounds?
Answer:
To answer, all living organisms contain carbon-based compounds, which classifies them organic.
Simply, carbon dioxide, is an example of an inorganic compound since it does not contain both carbon and hydrogen. Alternatively, one molecule of carbon dioxide contains one atom of carbon and two atoms of oxygen.
The force of attraction between one polar molecule and another polar molecule is
Answer:
Dipole-dipole forces
Explanation:
A polar compound is that compound which contains atoms that have a difference in charges i.e electrostatic attraction occurs between its constituent atoms. Polar molecules are attracted to other polar molecules with opposite charges and her held together with the aid of certain forces
The attractive force between the negative part of a polar molecule (-) and the positive part of another polar molecule (+) is called DIPOLE-DIPOLE FORCES. This dipole-dipole force gets stronger with an increasing polarity of the molecules involved.
Which type of bond will chromium atoms likely to form with other chromium atoms
A:ionic
B:covalent
C:metallic
Answer: B
Explanation: Covalent bonds where electrons are not shared equally between two atoms are called polar covalent bond. As shown above, the electrons in a covalent bond between two different atoms (H and Cl in this case) are not equally shared by the atoms. This is due to the electronegativity difference between the two atoms.
There are two types of chemical compound one is covalent compound and other is ionic compound in chemistry. The covalent bond will be formed between two chromium atoms. the correct option is option B.
What is chemical Compound?Chemical Compound is a combination of molecule, Molecule forms by combination of element and element forms by combination of atoms in fixed proportion.
Covalent bond formed by sharing of electron and ionic bond formed by complete transfer of electron.
Element with same electronegativity difference combine together by covalent bond whereas ionic bond is formed by elements whose electronegativity difference is high.
As two chromium is combining that is two two element with same electronegativity is combining therefore, formation of covalent bond is the only possibility.
Therefore covalent bond will be formed between two chromium atoms. the correct option is option B.
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Why are liquid and gas molecules different
How would an invasive species affect an ecosystem?
Group of answer choices
The invasive species would integrate easily into the ecosystem.
The invasive species would take over in the area and throw off the balance of the ecosystem.
The invasive species would balance the ecosystem.
The invasive species would change the abiotic factors in the area.
Answer:
The invasive species would take over in the area and throw off the balance of the ecosystem.
Explanation:
Invasive species can harm both the natural resources in an ecosystem as well as threaten human use of these resources. An invasive species can be introduced to a new area via the ballast water of oceangoing ships, intentional and accidental releases of aquaculture species, aquarium specimens or bait, and other means.
Invasive species are capable of causing extinctions of native plants and animals, reducing biodiversity, competing with native organisms for limited resources, and altering habitats. This can result in huge economic impacts and fundamental disruptions of coastal and Great Lakes ecosystems.
Hope this helped!
A balloon filled with helium occupies 21.0ft³ at 55.0°F. Find the temperature of the helium if the volume of the balloon decreases to 11.0ft³. (Assume that the pressure is held constant.)
Answer:
Assuming pressure is held constant,the question reduces to a ratio and proportion type of question where;
At constant pressure,
21.0ft³-55.0°F
11.0fy³=11.0ft³/21.0ft³×55°F
The temperature is 28.809°F≈29°F
29°F is the temperature of the helium if the volume of the balloon decreases to 11.0ft³.
What is temperature?Temperature expresses hotness and coldness or a measure of the average kinetic energy of the atoms or molecules in the system.
Assuming pressure is held constant, the question reduces to a ratio and proportion type of question where;
At constant pressure,
21.0ft³- 55.0°F
11.0fy³ = 11.0ft³ ÷ 21.0ft³ × 55°F
The temperature is 28.809°F ≈ 29°F
Hence, 29°F is the temperature of the helium if the volume of the balloon decreases to 11.0ft³.
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the first 5 elements (in increasing order) that are found in group 18
Answer:
Today, I will present the first eighteen elements which are Hydrogen, Helium, Lithium, Beryllium, Boron, Carbon, Nitrogen, Oxygen, Fluorine, Neon, Sodium, Magnesium, Aluminum, Silicon, Phosphorus, Sulfur, Chlorine, and Argon.
First 5: Hydrogen. The first and simplest element on the periodic table.
Helium. a very light colorless element that is one of the six inert gasses.
Lithium. A very soft, light metal.
Beryllium. A very light metal; although it is 3 1/2 times the density of Lithium.
Boron. The fifth element in the periodic table.
Explanation:
What is the mass 5.00 x 1022 molecules of PbCI2
Answer:
ion know this one
Explanation:
What is the number of protons for the following?
190
+2
Os
76
Answer:
190+2=192
Explanation:
192 add it 192 added
Answer: they are right
Explanation:
Which of the following interactions would be the strongest?
A. H2O and CH4
B. CH4 and CF4
C. H2O and HBr
D. HBr and CH4
Answer:
i think is c,my ans will not be 100%correct
Lily replicates an experiment that found that the number of calories in a particular food is 50 kcal. She obtained data from five trials: 50 kcal, 72 kcal, 50 kcal, 12 kcal, and 50 kcal.
Which best describes her data results?
accurate
incorrect
invalid
precise
PLEASE HURRY IM TIMED
Answer:
the best that describes her data result is precise
Which element wants to gain valence electrons while bonding?
a. Neon (Ne)
b. Fluorine (FI)
c. Lithium (Li)
d. Magnesium (Mg)
Answer:
b. Fluorine (FI)
Explanation:
From the given choices, only fluorine wants to gain valence electrons while bonding.
This is because fluorine is the most electronegative specie from the given choices. An electronegative substance have a high tendency to attract electrons to itself in a bond.
Neon is a noble gas and it is stable. Lithium and Magnesium are metals that are electropositive. They prefer to lose electrons than to gain electrons.In chemistry class, Allen determined the effectiveness of various metals in releasing hydrogen gas from hydrochloric acid. Several weeks later, Allen read that a utilities company was burying lead next to iron pipes to prevent rusting. Allen hypothesized that less rusting would occur with the more active metals. He placed the following into 4 separate beakers of water: (a) 1 iron nail, (b) 1 iron nail wrapped with an aluminum strip, (c) 1 iron nail wrapped with a magnesium strip, and (d) 1 iron nail wrapped with a lead strip. He used the same amount of water, equal amounts (mass) of the metals, and the same type of iron nails. At the end of 5 days, he rated the amount of rusting as small, moderate, or large. He also recorded the color of the water. What is the independent variable?
a) the amount of water
b) the metals strips
c) amount of rust
d) hydrochloric acid
Answer:
b) the metals strips
Explanation:
In an experimental design, an independent variable is a variable that is changed or manipulated in a series of experiments. An independent variable is not dependent on any other variable in the experiment. The hypothesis for this experiment is stated to be: "If the chemical activity of the metallic wrapper is increased, then less rusting of iron will occur. The independent variable relates to the type of metal wrapping strip, and the dependent variables are the amount of rusting and color of the water.
Please can anyone help me? How are the first 20 elements of the periodic table constructed?
Answer:
Based on the periodic law
Explanation:
All the elements on the periodic table were constructed based on the periodic law.
Henry Moseley in the 1900s re-stated the periodic law by changing the basis of the law from atomic weight to atomic number. The present periodic law is therefore "the properties of elements are a periodic function of their atomic number".
The atomic number is the number of protons in an atom. Based on the graduation of atomic number on the periodic table, elements are classified into groups and periods.In 25 words or fewer, what do you think a scientist would want to explain about this soda?
Answer:
This soda is brown, sweet, has high carbonation, and is about 200 calories when consumed.
Explanation:
:)
“Different periods in human history are named for the materials used to make tools. Dr. Franklin is searching through layers of soil, looking for tools made by humans. After screening the top layer of soil, he uses a magnet to help speed up the search.”
Which type of location is Dr. Franklin most likely searching?
A) a cave from before the Stone Age
B) a Stone Age cave
C) a Bronze Age battle site
D) an Iron Age farm
Answer:
Iron age farm
Explanation:
edge 2020
Answer:
D
Explanation:
Got it right on edge
Plants make their own food and are not required to consume food for energy. Into which category does this characteristic cause plants to be assigned?
Answer:
Autotrophic or Producers
Explanation:
They are often called producers because they make their own food.
10 divided by 2 im confused
if your serious about this question then it is 5
At 303 K, the volume of a gas is 30.0 ml. At constant pressure, what is the new
volume of the gas if the temperature is decreased to 283K?
Answer:
V₂ = 28 mL
Explanation:
Given data:
Initial temperature = 303 K
Initial volume = 30.0 mL
Final temperature = 283 K
Final volume = ?
Solution:
The given problem will be solve through the Charles Law.
According to this law, The volume of given amount of a gas is directly proportional to its temperature at constant number of moles and pressure.
Mathematical expression:
V₁/T₁ = V₂/T₂
V₁ = Initial volume
T₁ = Initial temperature
V₂ = Final volume
T₂ = Final temperature
Now we will put the values in formula.
V₁/T₁ = V₂/T₂
V₂ = V₁T₂/T₁
V₂ = 30.0 mL × 283 K /303 K
V₂ = 8490 mL.K / 303 K
V₂ = 28 mL
PLEASE HELP I'LL MARK BRAINLIEST
Describe, on the molecular level, why my glasses get fogged up when I wear my face mask (so dang annoying). Be sure to use these terms: -decreased kinetic energy -surface -attraction
Answer:
When you are in a cool place and exhale into your mask, the mask blocks and re-directs some of your breath up toward the top edge of the mask and under your glasses. ... When the warm breath hits the cool lens, the water in the breath condenses causing your lenses to fog up.
Also can someone help me with this one as well, thank you! :)
Answer:
a. The density of the aluminum will change if the sample gets too big.
Explanation:
Since increasing its size increases its volume hence it affects the value of its density by decreasing.
note: Density = mass/volume.
Bobbye wants to know how his speed affect the amount of time it takes to stop at a stop sign. Each time he performs a trial, he will change the speed that he is driving to see how it affects the amount of time it takes to stop. Independent Variable: Dependent Variable: Controlled Variables:
Answer:
The correct answer is -
Independent Variable: change of speed
Dependent Variable: time takes to stop
Controlled Variables: stop at a stop sign
Explanation:
To know the effect of the speed to take the time to stop at a stop sign Bobbye perform this exercise where he changes the speed at each time that he is driving to know the time it takes to stop at a stop sign. There is a change that takes place purposely is in the speed of driving so it is an independent variable as the independent variable is a variable that is manipulated in an experiment or investigation.
The time it takes to stop is the factor that depends on the speed so it is the dependent variable as the dependent variable is the variable that depends on the independent variable.
The control variable remains the same or constant in an investigation which is stoping at a stop time irrespective of speed.
Magnesium reacts with hydrochloric acid to produce hydrogen gas and magnesium chloride. What
volume of hydrogen gas is theoretically produced in cubic millimeters, if 4.9 g magnesium reacts
with excess hydrochloric acid? The reaction is taking place at 101.5 kPa pressure and 20°C.
using PV=mRT/Mr
V=(4.9×8.31×(273+20))/(24.3×101.5×10^3)
=4.84×10^-3 m^3
=4.84×10^6 mm^3
BRAINLEST WILL BE GIVEN TO A RIGHT ANSWER!!!!
Potassium (K) has a charge of +1, and sulfur has a charge of –2. Which best describes the compound they make?
A) The chemical formula is K2S, and the name is potassium sulfide.
B) The chemical formula is KS2, and the name is potassium sulfide.
C) The chemical formula is K2S, and the name is sulfur potassium.
D) The chemical formula is KS2, and the name is sulfur potassium.
Answer:
A) The chemical formula is K2S, and the name is potassium sulfide. Explanation:
edge
A metal atom and a non-metal atom bond together. What type of bond do they form?
Question 8 options:
Ionic
Round
Covalent
Glue
Answer: Iconic
Explanation:Ionic bonds are formed through the exchange of valence electrons between atoms, typically a metal and a nonmetal.
Name a molecule that is small enough to enter the cell
protein molecule
starch molecule
oxygen molecule
nitrogen
Answer:
oxygen molecule
Explanation:
I belive it is oxygen molecule
Answer:
Oxygen Molecle
Explanation:
I think that it is an oxygen molecule because oxygen can go through and or everything.
What are the first two levels of cellular organization?
Answer:
Cells and tissue
Explanation:
Cells are the smallest functional units of all living things
Tissue is organic material from which organs and their bodily structures appear